I am super new to knitting - and I have knitted a long skinny piece in stockinette. It is about 3 inches wide by 5 feet long. My random thought was to knit strips in this length and width alternating garter with stockinette (for practice). How do I start a new piece and bind it to the existing strip? I want to add to the 3 inch width another 3 inch strip by 5 feet long, repeating. Does that make any sense?

Sorry if this is confusing, I'm not quite sure how to explain it. I didn't see anything that would help me in the video section...

Oh, also...should I be knitting the stripes separately and joining them after, or should I be joining them as I knit? (I'm guessing the latter, but I am really clueless!)